Mount apparatus for mounting a measurement device on a rail car

ABSTRACT

A mount apparatus for mounting a measurement device on a rail car above a track surface of a railroad track including a securement member adapted to be secured to the unsprung component of the rail car, a pivot arm pivotably connected to the securement member, the pivot arm including a lever arm extending therefrom, and a swing arm connecting the lever arm of the pivot arm to the sprung component of the rail car. The swing arm rotates the pivot arm so that a distal end of the pivot arm is maintained at a substantially fixed height distance above the track surface.

This application claims priority to U.S. Provisional Application No.60/442,537, filed Jan. 27, 2003, the contents of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed to a mount apparatus for mounting ameasurement device on a rail car. In particular, the present inventionis directed to a mount apparatus that is movably secured to a rail carwhich maintains a substantially fixed vertical position relative to thetrack surface of a railroad track.

2. Description of Related Art

Various types of rail cars with different types of axle suspensionsystems are known and used in the railroad transportation industry forrail cars of freight and passenger trains. Axle suspension systems servean important function in that they suspend and stabilize the rail carsby allowing the wheels of the rail cars to move relative to the frame ofthe rail car body. Thus, the axle suspension systems allow wheels of therail car to absorb impact which occurs as the wheels roll along thetrack surface of the railroad track. The axle suspension systems alsoallow isolation of the rail car to provide a more comfortable ride topassengers of passenger rail cars having axle suspension systems.

Generally axle suspension systems include trucks having axles withwheels attached thereto. The axles are typically mounted to the truckvia axle bearing housings, suspension links which locate the axlebearing housings, and springs which suspends the truck over the axles.The rail car body is secured over the truck, with or without othersuspension components between the rail car body and the frame of thetruck. Thus, the wheels, the axles, and the axle bearing housings areunsprung components of the axle suspension system whereas the truckframe of the axle suspension component is a sprung component.

U.S. Pat. No. 4,356,775 to Paton et al. shows one example of a dampenedrailway car suspension including a movable load arm assembly forsupporting a rail car axle. The load arm assembly to which the axle isattached is movable relative to the truck and thus, is movable relativeto the rail car itself. Such movable load arm assemblies allow use ofsprings and dampeners to absorb impact which occurs as the wheels rollalong the track surface of the railroad track. By providing suchsuspension, the wheels of the rail cars are better controlled and theride quality of the rail cars is improved as previously noted.

U.S. Pat. No. 5,001,989 to Mulcahy et al. shows another example of asingle axle suspension system for rail car truck. Mulcahy et al.discloses a single axle railway truck having an axle box with springsupport for suspending the frame of the rail car. The suspension systemdisclosed in Mulcahy et al. also includes a lateral traction rod whichis supported by the single axle and secured to the side frame of therail car, the lateral traction rod being a component of the suspensionsystem.

Further, rail condition is a very important aspect of rail transitsafety. Any damage or defects in the track surface, the railroad trackalignment, and other rail parameters can cause derailment of the railcar which will result in significant property damage and possible injuryto the train operators, passengers, and bystanders. Consequently,continual inspections are made to ensure that the railroad tracks are ingood condition so that chances of derailment are minimized.

In the above regard, measurement devices such as electronic sensors andother mechanical/electro-mechanical devices are now being used invarious ways to monitor the condition of the railroad tracks and thetrack surface. Such sensors and other measurement devices utilize laser,optical, magnetic, or other mechanical/electromechanical technologies tomeasure various parameters of the track surface and alignment of therailroad track so that the condition of the track surface and therailroad track can be monitored.

SUMMARY OF THE INVENTION

Mounting of measurement devices such as electronic sensors and othersuch devices for monitoring track conditions is a significant limitationin obtaining accurate data and information regarding the railroad trackand the track surface. This limitation is due to the fact that suchmeasurement devices are typically attached to the truck frame or therail car frame, proximate to the railroad track. Because both the truckframe and the rail car frame are sprung components which are suspendedby an axle suspension system, such as those previously described, thesecomponents correspondingly move vertically relative to the railroadtrack and the track surface with the rail car as it moves along therailroad track. As a result, the vertical position of the measurementdevices relative to the railroad track varies significantly as the railcar moves along the railroad track. This impedes obtaining of meaningfuldata and information regarding the condition of the railroad track, suchas dimensional parameters of the track surface and/or the railroad trackalignment.

To compensate for the variation in the vertical position of themeasurement devices, measurement range may be increased if themeasurement devices allows such an increase. This typically results inlower measurement resolution and accuracy. However, providing highresolution is desirable when measuring various parameters such as railcorrugation and condition, track surface, track alignment, and the like.Consequently, effective monitoring of the railroad track condition andtrack surface for damage or defects cannot be readily attained usingpresently available methods or devices for mounting such measurementdevices.

In view of the foregoing, one aspect of the present invention isproviding a mount apparatus for mounting measurement devices on a railcar.

One advantage of the present invention is in providing such a mountapparatus that maintains a substantially fixed vertical positionrelative to the track surface of a railroad track.

Still another advantage of the present invention is in providing such amount apparatus which is mounted to an axle bearing housing of a railcar truck.

In accordance with one aspect of the present invention, a mountapparatus for mounting a measurement device on a rail car above a tracksurface of a railroad track is provided, the rail car having an unsprungcomponent and a sprung component. The mount apparatus comprises asecurement member adapted to be secured to the unsprung component of therail car, a pivot arm pivotably connected to the securement member, thepivot arm including a lever arm extending therefrom, and a swing armconnecting the lever arm of the pivot arm to the sprung component of therail car. The swing arm rotates the pivot arm so that a distal end ofthe pivot arm is maintained at a substantially fixed height distanceabove the track surface.

In accordance with one embodiment, the securement member is implementedas a cradle member which is adapted to be secured to an axle bearinghousing of a rail car truck, the cradle member including a semi-circularaxle bearing housing portion. In another embodiment, one end of thepivot arm is pivotably connected to the securement member by a bearing,and the distal end of the pivot arm is provided with a cross bar mountfor mounting a cross bar that laterally extends above the track surface.

In accordance with other embodiments of the present invention, the leverarm of the pivot arm may be implemented as an extension flange. Theswing arm may be connected to a truck frame and be implemented to allowadjustment to the length of the swing arm. For example, the swing armmay include a threaded stud member and one reverse threaded end thatallows adjustment to its length.

In accordance with yet another embodiment of the present invention, amount apparatus for mounting a measurement device on a rail car above atrack surface of a railroad track is provided, the mount apparatuscomprising a securement member adapted to be secured to the unsprungcomponent of the rail car, a pivot arm pivotably connected to thesecurement member and having a lever arm extending therefrom, and aswing arm connecting the lever arm of the pivot arm to the sprungcomponent of the rail car. The swing arm rotates the pivot arm in amanner to move a distal end of the pivot arm a vertical distance thatoffsets a vertical distance moved by the sprung component relative tothe unsprung component.

In accordance with still another aspect of the present invention, amethod for mounting a measurement device on a rail car is provided, themethod comprising the steps of securing the measurement device above atrack surface of a railroad track, and moving the position of themeasurement device in response to movement of the sprung componentrelative to the unsprung component, thereby maintaining position of themeasurement device at a substantially the same fixed height distanceabove the track surface.

In accordance with another embodiment, the method may further includethe steps of securing the measurement device to a mounting apparatus,and moving the position of the mounting apparatus in response tomovement of the sprung component relative to the track surface, therebymoving the position of the measurement device. In one implementation,the mounting apparatus may include a securement member, a pivot arm witha lever arm extending therefrom, and a swing arm. In this regard, themethod may further include the steps of securing the securement memberto the unsprung component of the rail car, connecting the pivot arm tothe securement member, and connecting the swing arm to the lever arm ofthe pivot arm and to the sprung component of the rail car. Thus, thepivot arm is rotated to move a distal end of the pivot arm a verticaldistance that offsets a vertical distance moved by the sprung componentrelative to the track surface. Moreover, in accordance with anotherembodiment, the method may further include the step of adjusting theposition of a distal end of the pivot arm based on an output of themeasurement device.

These and other features of the present invention will become moreapparent from the following detailed description of the preferredembodiments of the present invention when viewed in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a mount apparatus for mounting ameasurement device on a rail car in accordance with one embodiment ofthe present invention.

FIG. 2 is a side profile view of the mount apparatus of FIG. 1 mountedto an axle bearing housing of a rail car truck.

FIG. 3 shows a perspective view of a cradle member in accordance withone embodiment of the present invention.

FIG. 4 is a partial schematic side profile view of the mount apparatusof FIG. 1 which is installed on an axle bearing housing of a rail cartruck.

FIG. 5 is a perspective view of a mount apparatus for mounting ameasurement device on a rail car in accordance with another embodimentof the present invention.

FIG. 6 is a partial schematic top view of the mount apparatus of FIG. 5which is installed on an axle bearing housing of a rail car truck.

FIG. 7 is a schematic perspective view of the mount apparatus of FIG. 5mounted on a rail car truck.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 and 2 illustrate various views of a mount apparatus 10 formounting one or more measurement devices such as electronic sensors orother mechanical/electro-mechanical devices on a rail car in accordancewith one embodiment of the present invention. As explained in furtherdetail below, the mount apparatus 10 is adapted to be movably secured tothe rail car so that a distal end of the mount apparatus 10 maintains asubstantially fixed vertical position relative to the track surface of arailroad track. This allows measurement devices such as electronicsensors and other devices that may utilize laser, optical, magnetic, orother technologies, to be readily mounted in the manner furtherdescribed below for monitoring track surface, railroad track alignment,and/or other parameters.

Referring to FIGS. 1 to 3, the mount apparatus 10 includes a securementmember that allows the mount apparatus 10 to be mounted to an unsprungcomponent of a rail car (not shown). In the illustrated embodiment, thesecurement member is implemented as a cradle member 12 which is mostclearly shown in FIG. 3. As shown in FIG. 2, the axle bearing housing 41is adapted to support an axle of the rail car about which the wheels ofthe rail car rotate to move the rail car along the railroad track. Thecradle member 12 is provided with a substantially semi-circular axlebearing receiving portion 15 that allows the mount apparatus 10 to besecured to axle bearing housing 41 with the axle bearing (not shown)disposed therein. As previously described, the axle bearing housing 41is an unsprung component of the truck of the rail car. The axle bearinghousing 41 is attached to suspension link 43 which is pivotably securedto the frame of the rail car truck at pivot 47. This allows the truckframe and the axle to move relative to each other, the truck frame beinga sprung component of the rail car truck.

The mount apparatus 10 in accordance with the illustrated embodimentalso includes a pivot arm 16 that is pivotably secured to the mount 13of the cradle member 12. In this regard, one end of the pivot arm 16 issupported on a bearing 18 at one end via the mounts 13 thereby allowingthe pivot arm 16 to pivot relative to the cradle member 12, the distalend of the pivot arm 16 being cantilevered as shown. In the illustratedembodiment of FIGS. 1 and 2, the mount apparatus 10 also includes across bar mount 20 provided at the distal end of the pivot arm 16, thecross bar mount 20 being adapted to secure a cross bar (not shown) thatmay be used to mount one or more measurement devices for measuringparameters of the railroad track. Of course, in other embodiments, themeasurement devices may be directly mounted to the pivot arm 16 insteadof a cross bar.

The pivot arm 16 of the illustrated embodiment is further provided withan extension flange 22 which extends from the pivot arm 16 and acts as alever arm for rotating the pivot arm 16 relative to the cradle member 12in a manner described herein. The mount apparatus 10 is further providedwith a swing arm 24 which, in the present embodiment, is substantiallyparallel to line “L” extending between the pivot 47 and the mount 13 ofthe cradle member 12 as shown in FIG. 2. One end 25 of the swing arm 24is hingably attached to the extension flange 22 at a position which is apredetermined distance from the pivot arm 16. The other end 26 of theswing arm 24 is attached to a sprung component of the rail car, forexample, the truck frame, at a point above the pivot 47. Thus, asubstantially parallel linkage structure is formed between the swing arm24 and the suspension link 43. Because the swing arm 24 is attached toextension flange 22 at a distance from the pivot arm 16, the pivot arm16 may be pivoted about the bearing 18 by rotation and/or displacementof the swing arm 24. Consequently, any movement of the rail car truckrelative to the axle bearing housing 41, or vice versa, causescorresponding rotation and/or displacement of the swing arm 24.

The mounting and use of the mount apparatus 110 is more clearly shown inFIG. 4. As shown, the mount apparatus 10 is secured to an unsprungcomponent of the rail car such as the axle bearing housing 41 using asecurement member, which in the present embodiment, is implemented asthe cradle member 12. A spring and a damper may be mounted between thetruck frame 40 and the axle bearing housing 41 like conventional railcar trucks, these components being omitted in FIG. 4 for claritypurposes.

As previously described, the pivot arm 16 is pivotable relative to thecradle member 12, the positioning of the pivot arm 16 being controlledby the swing arm 24 via the extension flange 22 in the presentembodiment. In particular, as the wheel 46 rotates about the axle 42along the rail 48 of a railroad track, there is relative movementbetween the sprung component and the unsprung component, i.e. the truckframe 40 and the axle 42. The movement may be caused by irregularitieson the surface of the track and/or wheel 46. Such relative movement mayalso be caused by objects on the track surface, or by the dynamicloading of the rail car body which can cause the rail car body and/ortruck frame 40 to pitch or roll. The movement of the truck frame 40relative to the axle bearing housing 41, or vice versa, causes the swingarm 24 to exert a displacing force to the extension flange 22 of thepivot arm 16 thereby causing the pivot arm 16 to rotate about thebearing 18 so that the distal end of the pivot arm 16 moves tocompensate for the relative movement.

In particular, as evident from careful examination of FIG. 4, the pivotarm 16 rotates counter clockwise about the bearing 18, away from therail 48, if the truck frame 40 is displaced downward toward the rail 48.Likewise, the pivot arm 16 rotates clockwise about the bearing 18,toward the rail 48, if the truck frame 40 is displaced upward away fromthe rail 48. Thus, the mount apparatus 10 in accordance with the presentinvention automatically rotates the pivot arm 16 in response to movementof the truck frame 40 relative to the axle 42.

In the preferred embodiment, the various components of the mountapparatus 10 are dimensioned so that the pivot arm 16 is rotated aboutthe bearing 18 so that the distal end of the pivot arm 16 at which thecross bar mount 20 is provided, maintains a substantially fixed heightdistance above the track surface of rail 48. In other words, the pivotarm 16 is rotated so that the cross bar mount 20 is moved a verticaldistance which offsets the vertical distance moved by the truck frame 40relative to the axle 42 thereby compensating for the relative movement.FIG. 4 also shows one embodiment of a cross bar 44 that is secured tothe cross bar mount 20 for providing easy mounting of one or moremeasurement devices such as electronic sensors and/or othermechanical/electro-mechanical devices for measuring various parametersof the rail 48. Thus, in the illustrated embodiment where the cross bar44 is secured to the cross bar mount 20, the cross bar 44 maintains asubstantially fixed height distance from the track surface of the rail48.

It should be noted that the lever arm in the illustrated embodiment isimplemented as the extension flange 22 to minimize stresses exertedthereon by the swing arm 24 to ensure durability of the mount apparatus10. Of course, the lever arm may be implemented as a conventionalstraight lever, or in any other appropriate manner. It should also benoted that whereas the swing arm 24 and the suspension link 43 aresubstantially parallel and of substantially equal length in theillustrated implementation, other geometries/dimensions may be used inother implementations as well. In addition, whereas FIG. 4 merelyillustrates one mount apparatus 10 mounted to one end of the axle 42, inoperation, another mount apparatus may be provided and mounted to theother end of the axle 42 at the other side of the rail car. This allowsthe cross bar 44 to extend across the width of the railroad track overboth of the rails of the railroad track (only one rail being shown), andfurther allows the cross bar 44 to be supported on both ends of the axle42 so as to reduce vibrations and/or oscillations thereof.

By providing a mount apparatus 10 which maintains a substantially fixedvertical position at the cross bar mount 20 from the track surface of arailroad track, the disadvantages and limitations of the prior artmounting methods can be readily minimized. Thus, the present inventionallows measurement devices such as sensors and othermechanical/electro-mechanical devices to be readily mounted to the railcar for monitoring and measuring parameters associated with the tracksurface, railroad track alignment, etc.

FIG. 5 is a perspective view of a mount apparatus 110 for mountingmeasurement devices such as sensors and the like on a rail car inaccordance with another embodiment of the present invention. As can beappreciated, the mount apparatus 110 is substantially similar to themount apparatus 10 described above relative to FIGS. 1 to 4. In thisregard, the mount apparatus 110 of FIG. 5 includes a cradle member 112that allows the mount apparatus 110 to be secured to an unsprungcomponent of the rail car such as an axle bearing housing. A pivot arm116 is secured to the cradle member 112 and is supported on a bearing118 that allows the pivot arm 116 to pivot relative to the cradle member112. A cross bar mount 120 is provided at the distal end of the pivotarm 116 to secure a cross bar 144 that may be used to mount one or moremeasurement devices.

The pivot arm 116 is further provided with an extension flange 122 thatacts as a lever arm in the manner previously described. The positioningof the pivot arm 116 is controlled by the swing arm 124 via theextension flange 122, the swing arm 124 being connected to a sprungcomponent of the rail car such as the truck frame 140. Thus, when thereis relative movement between the truck frame 140 and the axle bearinghousing to which the mount apparatus 110 is mounted, the swing arm 124compensates for the relative movement by pivoting the pivot arm 116about the bearing 118.

In accordance with the illustrated embodiment of FIG. 5, the swing arm124 is also made so that its length is adjustable. As shown, the end 125of the swing arm 124 that is hingably attached to the extension flange122 is threaded to a stud member 127 so that the position of the end 125relative to the stud member 127 may be adjusted. Likewise, the other end126 of the swing arm 124 which is attached to the truck frame of therail car, is also threaded to the stud member 127 so that the positionof the end 126 relative to the stud member 127 may be adjusted.Preferably, one of the ends is reverse threaded so that positions ofboth ends 125 and 126 can be simultaneously adjusted by rotating thestud member 127. Thus, by adjusting the position of end 125 and/or end126 on the stud member 127, the length of the swing arm 124 can bereadily adjusted.

This adjustability of the swing arm 124 allows the initial position ofthe pivot arm 116 to be adjusted so that the position of the measurementdevices, such as sensors that are secured to the distal end of the pivotarm 116, can be adjusted as well. This allows accurate measurements tobe attained because the measurement devices can be initially positionedto optimize their accuracy and sensitivity and moved to maintain thisoptimal position over the track surface. In addition, the measurementdevices themselves can be used to facilitate proper adjustment of theswing arm 124. For example by monitoring output or measurement readingsof the measurement devices while adjusting the length of the swing arm124, the optimal positioning of the pivot arm 116, and thus, themeasurement devices may be obtained. Of course, in other embodiments,the adjustability of the swing arm 124 may be actively controlled sothat the height adjustment may be finely tuned, for example, by usingthe output of the measurement device, or using a computational device.

FIG. 6 is a partial schematic top view of the mount apparatus 110 ofFIG. 5 shown installed on an axle bearing housing 141 of a rail car. Thesuspension link is omitted in FIG. 6 to enhance clarity. As shown andalready described relative to the other embodiment, the pivot arm 116 ismounted so that it is pivoted by the swing arm 124 to compensate for therelative movement between the truck frame 140 and the axle 142, andcorrespondingly, between the truck frame 140 and the track surface 148.In addition, FIG. 6 clearly illustrates the cross bar 144 which isattached to cross bar mount 120 that allows easy mounting of electronicsensors and/or mechanical/electromechanical devices for measuringvarious parameters of the rail 148.

FIG. 7 is a schematic perspective view of the mount apparatus 110 ofFIGS. 5 and 6 which also shows the structure of the truck frame 140 andhow the mount apparatus 110 functions. In addition, FIG. 7 also shows asecond mount apparatus provided and mounted to the other end of the axle142 so as to allow the cross bar 144 to extend across the width of therailroad track and be supported on both ends of the axle 142. Thisallows easy mounting of one or more measurement devices such aselectronic sensors and/or mechanical/electro-mechanical devices formeasuring various parameters of the rail 148 and the railroad track. Itshould be evident that the position of the cross bar 144 can be readilyadjusted by adjusting the length of the swing arm 124 in the mannerpreviously described.

In view of the above, it should further be evident that the presentinvention also provides a method for mounting one or more measurementdevices on a rail car where the rail car includes a rail car truck withan unsprung component such as an axle, and a sprung component such as atruck frame. In particular, the method includes the steps of securing ameasurement device above a track surface of a railroad track, and movingthe position of the measurement device in response to movement of thesprung component relative to the track surface. Thus, the method, asdescribed, maintains the position of the measurement device atsubstantially the same fixed height distance above the track surface andcompensates for the movement of the sprung component.

More specifically, in accordance with one preferred embodiment, themethod further includes the steps of securing the measurement device toa mounting apparatus, and moving the position of the mounting apparatusin response to movement of the sprung component of the rail car relativeto the unsprung component, thereby moving the position of themeasurement device. In another embodiment, the mounting apparatusincludes a securement member, a pivot arm with a lever arm extendingtherefrom, and a swing arm. In such an embodiment, the method furtherincludes the steps of securing the securement member to the unsprungcomponent of the rail car, connecting the pivot arm to the securementmember, and connecting the swing arm to the lever arm of the pivot armand to the sprung component of the rail car. This causes the pivot armto rotate in response to the relative movement so that a distal end ofthe pivot arm is moved a vertical distance that offsets the verticaldistance moved by the sprung component relative to the track surface.Moreover, the method may also include the step of adjusting the positionof the distal end of the pivot arm using the measurement device.

While various embodiments in accordance with the present invention havebeen shown and described, it is understood that the invention is notlimited thereto. The present invention may be changed, modified andfurther applied by those skilled in the art. For example, whereas in theillustrated embodiments discussed above, the mount apparatus wasprovided with a cradle member that is secured to an axle bearinghousing, it may also be secured to another component of the rail carsuch as another part of the suspension link. In addition, where thelever arm is preferably implemented as a flange member, an elongatedmember that extends from the pivot arm may be used instead. Therefore,this invention is not limited to the detail shown and describedpreviously, but also includes all such changes and modifications.

1. A mount apparatus for mounting a measurement device on a rail carabove a track surface of a railroad track, the rail car having anunsprung component and a sprung component, said mount apparatuscomprising: a securement member adapted to be secured to the unsprungcomponent of the rail car; a pivot arm pivotably connected to saidsecurement member, said pivot arm including a lever arm and a distal endthat is cantilevered above the track surface of the railroad track; anda swing arm connecting said lever arm of said pivot arm to the sprungcomponent of the rail car, said swing arm being adapted to rotate saidpivot arm so that said distal end of said pivot arm is maintained at asubstantially fixed height distance above the track surface.
 2. Themount apparatus of claim 1, wherein said securement member is a cradlemember adapted to be secured to an axle bearing housing of a rail cartruck.
 3. The mount apparatus of claim 2, wherein said cradle memberincludes a semi-circular axle bearing housing portion.
 4. The mountapparatus of claim 1, wherein one end of said pivot arm is pivotablyconnected to said securement member by a bearing.
 5. The mount apparatusof claim 1, wherein said lever arm of said pivot arm is an extensionflange.
 6. The mount apparatus of claim 1, wherein said swing arm isconnected to a truck frame.
 7. The mount apparatus of claim 1, whereinlength dimension of said swing arm is adjustable.
 8. The mount apparatusof claim 7, wherein said swing arm includes a threaded stud member andone reverse threaded end.
 9. The mount apparatus of claim 1, whereinsaid measurement device is an electronic sensor.
 10. A mount apparatusfor mounting a measurement device on a rail car above a track surface ofa railroad track, the rail car having an unsprung component and a sprungcomponent, said mount apparatus comprising: a securement member adaptedto be secured to the unsprung component of the rail car; a pivot armpivotably connected to said securement member, said pivot arm includinga lever arm and a distal end that is cantilevered above the tracksurface of the railroad track; and a swing arm connecting said lever armof said pivot arm to the sprung component of the rail car, said swingarm being adapted to rotate said pivot arm so that said distal end ofsaid pivot arm is maintained at a substantially fixed height distanceabove the track surface; wherein one end of said pivot arm is pivotablyconnected to said securement member by a bearing; wherein said distalend of said pivot arm is provided with a cross bar mount.
 11. The mountapparatus of claim 10, further comprising a cross bar laterallyextending above said track surface, said cross bar being mounted to saidcross bar mount.
 12. A mount apparatus for mounting a measurement deviceon a rail car above a track surface of a railroad track, the rail carhaving an unsprung component and a sprung component, said mountapparatus comprising: a securement member adapted to be secured to theunsprung component of the rail car; a pivot arm pivotably connected tosaid securement member, said pivot arm including a lever arm and adistal end that is cantilevered above the track surface of the railroadtrack; and a swing arm connecting said lever arm of said pivot arm tothe sprung component of the rail car to rotate said pivot arm in amanner to move said distal end of said pivot arm a vertical distancethat offsets a vertical distance moved by said sprung component relativeto the unsprung component.
 13. The mount apparatus of claim 12, whereinsaid securement member is a cradle member with a semi-circular axlebearing housing portion adapted to be secured to an axle bearing housingof a rail car truck.
 14. The mount apparatus of claim 12, wherein oneend of said pivot arm is pivotably connected to said securement memberby a bearing.
 15. The mount apparatus of claim 12, wherein said leverarm of said pivot arm is an extension flange, and said swing arm isconnected to a truck frame and said extension flange.
 16. A mountapparatus for mounting a measurement device on a rail car above a tracksurface of a railroad track, the rail car having an unsprung componentand a sprung component, said mount apparatus comprising: a securementmember adapted to be secured to the unsprung component of the rail car;a pivot arm pivotably connected to said securement member, said pivotarm including a lever arm and a distal end that is cantilevered abovethe track surface of the railroad track; and a swing arm connecting saidlever arm of said pivot arm to the sprung component of the rail car torotate said pivot arm in a manner to move said distal end of said pivotarm a vertical distance that offsets a vertical distance moved by saidsprung component relative to the unsprung component; a cross barlaterally extending above said track surface, said cross bar beingmounted at a distal end of said pivot arm.
 17. A method for mounting ameasurement device on a rail car, the rail car having an unsprungcomponent and a sprung component, said method comprising the steps of:securing said measurement device above a track surface of a railroadtrack in a cantilevered manner; and moving the position of saidmeasurement device in response to movement of the sprung componentrelative to the unsprung component, thereby maintaining position of saidmeasurement device secured in a cantilevered manner at a substantiallythe same fixed height distance above the track surface.
 18. The methodof claim 17, further including the step of securing said measurementdevice to a mounting apparatus and moving the position of said mountingapparatus in response to movement of the sprung component relative tothe track surface, thereby moving the position of said measurementdevice.
 19. The method of claim 18, wherein said mounting apparatusincludes a securement member, a pivot arm with a lever arm extendingtherefrom, and a swing arm.
 20. The method of claim 19, furtherincluding the steps of: securing said securement member to the unsprungcomponent of the rail car; connecting said pivot arm to said securementmember; and connecting said swing arm to said lever arm of said pivotarm and to the sprung component of the rail car, so that said pivot armis rotated to move a distal end of said pivot arm a vertical distancethat offsets a vertical distance moved by said sprung component relativeto the track surface.
 21. The method of claim 19, further including thestep of adjusting the position of a distal end of said pivot arm basedon an output of said measurement device.